Descriptions

Early afternoon environmental conditions preceding hail-producing thunderstorms are statistically compared with conditions for classes of less severe moist convection using only data from individual radiosonde releases collected during the National Hail Research Experiment in northeast Colorado. The ensuing analyses emphasize the thermodynamic characteristics of the mixed layer and immediate overlying free flow.
On days with hail-producing thunderstorms, the mixed layer tends to be particularly thin and moist. Energy required to initiate moist convection is found to be somewhat greater than normal, while energy required to further develop moist convection is substantially less than normal. Parcel energies are found to be quite sensitive to the level of parcel origin in the mixed layer.